Help Find A Cure for Crazcnuk's bike?

[Crazcnuk]

Heh, yes, but if you notice, no needles in the 80-81 kits!

[dbeardslee]

Craz - In the immortal words of Homer Simpson - Doh!

[egsols]

Hey dbeardslee,

I picked up a set of those kits for a '79. I mainly wanted the float valves, seats and bowl gaskets. I wasn't that happy with the valves, seem to be a poor quality finish.

One of these days, I'm going check the jets to see if they are actually the right size although everything is stamped with the stock sizes on them. About the only thing you don't get in the kits are the emulsion tubes.

$15 per set does beat $40 for a valve and seat, only, from the local dealer up here.

[dbeardslee]

Egsols - I wasn't too worried about the jets as I can't use the ones that come in a set anyway. They become 'experimental jets' as soon as I open the pack. I've been wanting to play around with drill bits and carb jets.

What I want out of a carb kit is new needles, needle and seats, gaskets, mixture screws and springs. $15 seemed like a fair price, and it looks like the same kit Z1 sells for $18. Asside from the looks, did the float valves work OK?

Craz - If this thread gets a little longer you'll be able to take it to a publisher and have it bound

[olebiker]

Originally posted by dbeardslee


Craz - If this thread gets a little longer you'll be able to take it to a publisher and have it bound

+1

[Crazcnuk]

Can't until it ends.

Until we actually FIX the damn thing, it ain't over....

Maybe it will be an epic.

[tarzan]

Does that mean your going to tear it down and rebuild it now?

[Crazcnuk]

I Have been tinkering on the other engine. I checked the rings, transmission etc, and now am just looking for some way to clean the crankcase, before I start to put it together.

I may need a different head gasket, but I think I have everything else I need to rebuild it.

Except for a heated garage to do it in....

[MotoMartin]

Have you checked that the CDI unit for the 1980 model is fully compatible with the 1981 motor? I had a WR426 bike with a YZ426 motor, the CDI units looked the same and worked to some degree but the performance was off by about 20%.

[Crazcnuk]

AS far as I can tell they are, but then how does one tell?

There are only 2 types, 78-80, and 81+. The engine I have has all the right parts to go with the box I have.

[egsols]

Hey dbeardslee,

The float valves didn't work okay, that was the problem. When I bench tested them one would leak. I tried using some chrome polish to smooth them out but I still couldn't get them to make a good seal. When I look at them under a magnifying glass I can clearly see milling marks so I am wondering about the quality of these valves. But hey what do you expect for 15 bucks. I know the dealer wants a heck of lot more but how do I know I not going to get the same aftermarket stuff that I have?

I eventually ended up getting a new set of virago valves and seats, off carbkitcapital. These valves have the viton tips and the seats are the same screw type. The only thing I had to change was to use the original fiber washer instead of the steel one and set my floats at 27.7mm to compensate for the slightly different height of the valves and seats. Haven't had a problem with leaking valves since. (Only the odd stuck float )

[egsols]

Hey Craz,

You're saying that when you adjust the needles, you can gain or loose the top end. Correct me if I'm wrong, (wouldn't be the first time and definitely not the last), but I thought the needles only took you up to about 5000rpm, above which they should be clear of the tubes to run mains only?

If the needles are affecting the running past 5000 then I would assume they are not clearing the tubes enough......needles too long..springs too weak, slides not going up fully, wrong taper profile...JAT

That might explain why your 120's looked good on the plugs if the needles were holding back the mains at the top. I'm also wondering if the adjustable needles are not a match to the 300 tubes you've got.

One last thing and I promise I'll stop rambling, I've haven't compared them but are the dimensions of the diaphragm assemblies the same between the adjustable and fixed? What I mean, is the slide the same overall height and are the bodies between the 79's and 80's the same also. If they are not it could prevent them from rising fully.

[Crazcnuk]

On the carbs that we have, all the circuits are in use all the time.

This means that even at full throttle the idle and mid range circuits are still in use.

If you look at the carb there is no provision to shut off any of the circuits. This is why you have to set the main first, before you do the mid range and idle settings.

I am not sure why I don't have any high end, so I can't say why changing the neelde height would affect it.

We are still not sure what the heck needles I have. The numbers on mine do not match ANY of the known carb configurations, although 1980 Canadian carbs, apparently did use adjustable needles.

AS far as I know my slides and diaphragms are the same as everyone elses, I don't know that there are different ones?

[dbeardslee]

Craz - I got looking back through this thread and saw that you haven't had the head off. I had to take the head off mine due to a leaking head gasket. I cleaned it up real good, hand-lapped the valves, replaced the stem seals, and set the valve clearances. It made a HUGE difference in the way it runs. I'm not saying it's what's causing your lack of top end (fuel volume, partially clogged or constricted vent-line?), but it's something to think about with winter comin' on.

[egsols]

Originally posted by Crazcnuk

I am not sure why I don't have any high end, so I can't say why changing the neelde height would affect it.

If I understand what you said previously, the top end gets worse when you drop the needles but the low end gets better. What I'm hearing is that the when the needles are lower the bike is running leaner which in turn helps the low end (previously too rich). If the needles sit lower in the tubes then I assume it restricts the fuel. Now, if the needles are effectively longer by this drop then when the slides go all the way up, a portion of the needle is still in the tube, restricting or causing a lean condition. Now, if the taper on the needle is too fat near the bottom then it wouldn't matter how high the needle goes, it could still be restricting the fuel coming throught the tube and causing lean at high end.

Have you tried running the needles full up, i.e. full rich? Bike probably wouldn't run worth a crap down low but it might tell you if it will give you more fuel at WOT. The fact that 120 mains, especially at your altitude, came back clean on the plugs leads to me to believe you are still too lean at WOT.